1. Field of the Invention
The present invention relates in general to an optical distance measurement apparatus using a pulse light beam, and more particularly to optical distance measurement apparatus and method using a cleaning device in which a pollution sensor is provided to sense pollution, the cleaning device being disposed over a front surface of a protecting glass to remove the sensed pollution, a diode abnormal state sensor being provided to sense an error of a light emitting laser diode using a photo diode for monitoring the light emitting laser diode and an error of a light receiving photo diode using a laser diode for monitoring the light receiving photo diode, wherein a time period in which a part of a pulse light beam from the light emitting laser diode is reflected from a reflection surface of the cleaning device and then received by the light receiving photo diode, is converted into error data and the converted error data is subtracted from a measured light moving time to an object, the error data resulting from a temperature variation, faulty operations of the components.
2. Description of the Prior Art
Conventional distance measurement equipments are mostly adapted to measure distances to objects using standard measurement devices with corresponding lengths.
On the other hand, a conventional optical distance measurement apparatus measures a light moving time and then a distance to an object on the basis of the measured light moving time and a light velocity. A precision in the distance measurement is dependent on the accuracy in the light moving time measurement. However, since a light beam moves 30 cm per 1 nsec, it is very difficult to measure accurately the light moving time. Namely, because the light moving time is very short, the measured light moving time may be different according to an external variation or self-variations of components and a pollution level on a front surface of the glass for protecting the components. For this reason, it is very difficult to measure accurately a light moving distance.
In other words, in such a conventional optical distance measurement apparatus, the front surface of the protecting glass may be polluted at any time due to external circumstances because it is exposed to the outside. Also, the presence of a faulty operation of a laser diode as an important component must be checked at fixed periods in the process. Further, according to a temperature, there may be a variation in the signal delay of components for receiving an emitted light beam, converting the received light beam into an electrical signal, amplifying the converted electrical signal and measuring the light moving time using the amplified electrical signal. Furthermore, the delay error may be generated due to deviations of products. In this case, a separate adjustment must be applied to every product, for compensation for the delay error. However, the delay error due to the temperature cannot be adjusted in use, resulting in an error in the measurement.